2006 as an ancillary study to the Longitudinal Assessment of Bariatric Surgery (LABS) study. Long range goals are to detail the outcomes of bariatric surgery in youth over multiple decades including multigenerational effects of treatment. The immediate goals are to address important gaps in our understanding of the impact of early onset obesity and the efficacy and safety of bariatric surgery in adolescents compared to adults. The primary achievements of Teen-LABS during the first funding cycle include; 1. establishment of a strong collaborative multi-institutional working group of investigators committed to Teen-LABS, 2. defining the principal domains of the study, building on the study design of the LABS consortium, 3. establishing a functional research infrastructure including multiple committees and a data coordinating center, 4. enrollment, as of January 31, 2011, of 83% of the planned 250 adolescent and caregiver participants, 5. initiating a 2 year outcomes study, 6. supporting the needs of 11 Teen-LABS ancillary and 4 substudies. In addition to documenting the immediate trajectories of weight loss, acute changes in comorbidities, and safety of bariatric procedures in adolescents over 2 years, a thorough examination of the durability and consequences of surgery beyond 2 years will address a major gap in our understanding of the long term outcome of bariatric surgery in this high risk group of patients. In the next 5 years, the consortium will concentrate on scientifically critical research questions that cannot be addressed with the limited follow-up that currently exists. In the renewal period, Teen-LABS will examine mid- and longer-term outcomes. An extension will permit Teen-LABS to continue to collect follow-up data in parallel with the LABS consortium, now already in their second funding cycle. Teen-LABS will be expanded and establish new relationships with experts in other disciplines to permit the evaluation of myriad emerging effects of surgery in a vulnerable patient population, as well as effects that change over time, and determine whether the response to surgery in adolescent age groups differs from adults. The research approach in this proposal will focus on 1) retention strategies that will maintain the cohort, insuring availability for longer term study and 2) dissemination of research findings from baseline characterization and early outcomes. An extension of Teen-LABS will build on the already productive five center research network, representing several care delivery systems and patient populations. Teen-LABS enrolls from four academic pediatric medical centers with dedicated adolescent bariatric programs and one adult academic center with a hybrid adult-adolescent bariatric program that jointly serves as a LABS/Teen-LABS site. We have collaboratively assembled a well-phenotyped adolescent cohort with a range of patient characteristics, and undergoing state of-the-art surgical procedures. The critical scientific strengths of the multicenter Teen-LABS consortium include a diverse participant base to insure generalizability of findings, the ability to recruit a large number of subjects including important subgroups, the use of an existing research infrastructure with meticulous and high quality baseline and follow-up data collection practices, and an outstanding group of clinician scientists who continues to contribute greatly to the interpretation of the findings from the studies. The data coordinating center will continue to insure very high levels of data accuracy and completeness so that the investigators will be able to produce a long list of publications addressing important research questions with clinical significance. This proposal describes the process by which the Teen-LABS study was initiated, the consortium's progress to date, and provides our goals for the next five years of study.